How much time should I allocate for transiting from the flight gate to the train station at Munich Airport?

Assuming you land at 7 sharp, and assuming there are other flights landing pretty much around the same time, I would suggest you to keep a buffer time of 2-2.5 hours. Whenever I have reached Munich, it took me 30-40 min to come out, but there have been cases when I waited for more than 1.5 hours when I went to receive my friends because there were 3-4 flights landing around the same time and few people at the passport control.

Once you are done with all these formalities, you need to take the S Bahn aka Suburban Train (look for a big green symbol with S written in white. You can buy the ticket at the airport itself. This walk to catch S Bahn + getting tickets totally must take you around 10 min max. There are frequent trains going to Munich central station where you need to catch your train to Austria. This journey to central station takes about 30-40 min if I am correct.

To save time, you can get the tickets to Austria online. Check Deutsche Bahn or OBB website. You can then catch the 9:28 one or the 11:28 one to Salzburg, and change trains to your destination: Vocklabruck, depending on how quickly you are done with passport control and baggage collection.

Have a safe journey!